Yes, by default REGASM created registry entries based on the strong name and looks in the GAC for the assembly. You can change that using the codebase attribute or by making the assembly a private assembly. In the latter case you would create manifest files with the entries rather than load them in the registry.
REGASM is part of the Framework, but GACUTIL is part of the SDK. You'll have to download and install the SDK to get it. See, for example:
http://stackoverflow.com/questions/6925043/where-is-gacutil-for-net-framework-4-0-in-windows-7
and
http://msdn.microsoft.com/en-us/library/ex0ss12c.aspx
"This tool is automatically installed with Visual Studio and with the Windows SDK."